Saxon Lesson 78
Vocabulary: (a) the distance between crests is.... (b) the # of waves per second is..... (c) the height of a crest is........
a) wavelength b) frequency c) amplitude
Are electric potential and potential energy the same? Why or why not?
Electric potential and potential energy are not the same. They have different physical units and therefore describe different physical phenomena.
(A) Capacitor, (B) Capacitance
Define an electric circuit. And draw one.
When electric charge travels through a conductor front one side of a battery to another, we call the system an electric circuit. (pg 487 textbook)
See figure 15.2 (pg 489 Textbook). Electrons actually flow from the negative side of the battery to the positive side. The long line is the positive and short line is the negative.
Define Electric Current and its equation.
The amount of charge that travels past a fixed point in an electric circuit each second. I = Delta Q / Delta t (page 488 textbook)
What is the difference between a NODE and an ANTINODE?
NODE = Where there is no movement along the wave or where the waves cancel each other out. ANTINODE = Where there is a maximum amount of movement and/or where amplification is greatest
A positive Particle is near a Stationery negative charge. Is the electric potential positive or negative? What about the potential energy of the positive particle?
The electric potential deal only with the Stationery charge. Thus the electric potential is NEGATIVE. AND The potential energy is calculated from multiplying the potential (which is negative) times the freely moving particle's charge (which is positive). Therefore the potential energy is NEGATIVE.
(A) What is a Dielectric Breakdown? (B)What is another word for dielectric?
(A)..When the dielectric fails to prevent the flowing or transfer of charge because the electric potential has become so large....(B) aka insulator.
"I" stands for electric current, but what is the actually unit for electric current and it's name?
Colulombs/second. Physicists call this unit the Ampere, "amp", "A" in honor of Andre Ampere, a physicist who studied electricity and magnetism. (pg 488 textbook)
If you pass a current through a conductor and measure the conductor's temperature, you will find that the temperature of the conductor increases as the current passes through it. Why?
All conductors have some resistance, and resistance will convert some of the current's kinetic energy into heat, which will raise the temperature of the conductor. (pg 261 test booklet)
The longest possible wavelength of a standing wave.
A negative Particle is near a Stationery positive charge. Is the electric potential positive or negative? What about the potential energy of the positive Particle?
The electric potential deals only with the stationery charge. Therefore, the electric potential is POSITIVE. The potential energy is calculated by multiplying the potential (which is positive) ties the freely moving particle's charge (which is negative). Thus, the potential energy is NEGATIVE.
A Negative Particle moves from the Negative plate of a Capacitor to the Positive plate. Is its change in electric potential Positive or Negative? Does its potential energy Increase or Decrease?
When a Particle moves from the Negative plate to the Positive plate, its CHANGE IN ELECTRIC POTENTIAL IS POSITIVE. To get the potential energy, however, we multiply by Particle's charge. Since the charge is Negative, the change in potential energy is Negative. Thus, THE POTENTIAL ENERGY DECREASES.
Two-part question: (a) Define Resistance and give an example. (b) What does resistance have to do with Ohm's Law? DOUBLE POINTS if you can do so without looking at your book or notes.
(a) The ability of a material to impede the flow of a charge when it is subject to a potential difference. (b) Ohm's Law is the relationship between the current in a conductor and that conductor's resistance. V=I*R (page 491-2 textbook).
What impact did Benjamin Franklin have in the domain of circuits? What was discovered, which revealed his error in thinking?
Benjamin Franklin was highly respected by scientists around the world. Since he though electrons flowed from the positive side of the battery to the negative side - scientists around the world (then and now) draw circuits that show the electrons moving from positive to negative, which is called conventional current. The electron was discovered. (pg 489 textbook)
A guitar who tension is fixed length (L=0.630m) and fundamental frequency of (f=440 HZ). What is the speed of the wave?
554 meters/second
A +2.3 mC charge is placed 35cm away from a Stationery charge. If it experiences an electric potential of -4.6 x 10 (7) volts, what is the value of the Fixed Charge?
The charge is -1.8 x 10 (-3) C. Page 96
In a 3.4 x 10 (3) volt potential, a particle has a potential energy of -12 J. What is the particle's charge?
-3.5 x 10 (-3) C Page 96
A motor has a resistance of 4.1 amps and uses a 7.0 volt power supply. What is the current that it draws?
Use Equation 15.2 V= IR Answer: 1.7 A (page 261 #8 on Module test)
If a resistor uses 98 Watts of power and draws 2.1 A of current, what is its resistance?
Use Equation 15.4 P= I(2)*R R = 22 (page 261 #9 on Module test)
What Length would give the string a fundamental frequency of 659 HZ? v=554 m/sec
Length = 0.421m
A -5.1 mC charge that is free to move is placed 2.20m from a Stationery +5.8 mC charge. If the freely moving charge moves 2.00 m towards the Stationery charge, what is the change in potential energy? Did it increase or decrease?
Decreased by 1.2 x 10 (6) J. page 97